Can U.S. West Coast climate be forecast?
Steve LaDochy, California State University, Los Angeles, CA; and J. N. Brown, M. Selke, and W. C. Patzert
The vast Pacific Ocean influences climates around the world, but especially along its coasts. U.S. west coast temperatures are moderated by the climatic shifts in and over the Pacific, and almost all U.S. west coast precipitation is controlled by these shifts in Pacific climate. In an earlier study, we found that the Pacific Decadal Oscillation (PDO) was a good forecaster for spring and summer temperatures, as well as the frequency of dense fog along the southern California coast. The present research indicates that Pacific oceanic and atmospheric indices can be used to forecast seasonal west coast temperatures and precipitation from Seattle to San Diego. Among the Pacific indices that best explain temperature variability, the PDO Index shows significant correlations at lead times of 1 to 4 seasons. About half the variability in annual temperatures along the west coast is explained by the PDO Index alone. The North Pacific Index (NP) explains up to 64% of the winter temperature variability along the Oregon and Washington coasts. While extratropical North Pacific indices explain temperatures along the coast, tropical Pacific conditions, such as the Southern Oscillation Index (SOI) are best at explaining variability in precipitation. The California coastal precipitation is negatively related to the SOI, Nino 3.4 and tropical Pacific SST EOF’s, while Washington and Oregon are positively related to these indices. Seasonally, Pacific indices are best at explaining winter and summer temperatures, and spring and fall precipitation. Using over 50 years of U.S. climatic, Pacific atmospheric and oceanic monthly data from NOAA’s National Climate Prediction Center (NCEP), NOAA’s NCEP Correlation tool, we were able to develop forecast models to explain temperature and precipitation variability for each west coast region. Decadal cycles were also found to be useful indicators of future regional climate variability.
Extended Abstract (1.6M)
Poster Session 2, Seasonal to interannual climate prediction with emphasis on the 2002 El Nino (Hall 4AB)
Thursday, 15 January 2004, 9:45 AM-9:45 AM, Hall 4AB
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